Process for the bronzing of copper and copper alloys



Sept. 15, 1936. A. BRUNNER 2,054,737

PROCESS FOR THE BRONZI NG OF COPPER AND COPPER ALLOYS Filed April 24, 1955 /nvent0P: Add W .1 the other process they are immersed in corre Patented Sept. I 15, 1936 I I I v UNITED STATES PATENT OFFICE 1,054,131 I PROCESS FOR THE BRONZING OF COPPER AND COPPER ALLOYS Adolf Brunner, Therwil, Switzerland, asslgnor to Metallwerke Ao' G- Dornach, Dornach/Baael, Switzerland Application April 24, 1935, Serial No. 19,520 In Germany May 2,1934

Claims. (01. 1486) The present invention relates to processes for The working operation of the process is as the bronzing of copper and copper alloys, more follows: particularly brass and special brass (Sondermes- The polished metal surface It which, if necessing). sary, is freed from grease, is rubbed down with 5 The customary methods for coloring copper a swab. which is slightly moistened with the 101- l and copper alloys brown are based principally lowing acid solution: on two processes: According to the one process water 1000 the metals are painted over or coatedseveral times with suitable solutions, whilst according to $35,315:?g ggfigfiggf fif gggggg Z2 sponding solutions. In both cases the metals This liquid causes, when applied to the metal, must be subjected to a subsequent treatment a slight corrosion of the surface. The slight with water and a scratch brush in order to obcoppering action which, in the case of brass, tain a uniform coloration and to impart the dealloys, arises at the same time acts very favorsired appearance to the surface. Even then b y t0 the Subsequent fdrmatlon of copper -1 there still remain darker and often black spots p de. The smell residues of acid still adheror patches, the elimination of h h frequently ing to the metal after the application are then amounts to an almost complete removal of the completely v d wit a d w b- Th n t bronzing. Further disadvantages of the proctly corroded surface t us p ep desses hitherto employed arise in metal constructhe! eated by causing a stream of gas congo tions employed in connection with brickwork. taming ammonium sulphide sweep In this case a, bronzing operation in situ is The necessary stream of gas is produced by passpossible, inasmuch as by t application f the ing air supplied from a compressed air container bronzing solution, the washing and the treat,- I or a hand-blower 2 into an apparatus 4, 6, l, 8

ment with the scratch brush, the adjacent wood Qompflsmg 9 container pemtmg in know framework, brickwork and soy forth would be- 1161" and through a solution of ammonium come soiled. Furthermore, if the parts have to pmde 5 of about 10-20% strength whereby the be treated by-immersion in the bronzing liquid, air becomes saturated with the latter The expensive vats are necessary for the immersion stream of gas 9 which is thus obtained process, particularly when large metal construcwhich contains ammonium sulphide is now 30 rected on to the metal surface In which is to be 3213 513 mfi $g g ?gg:: bronzed and which has been slightly corroided I The to the e is smarter vention eliminates the aforesaid defects in a about 5-10 cm. between the metal surface I0 .35 simple manner. The process is characterized in and the nozzle opening a of the bottle 4 5 1 3 that the polished metal surface which if neces' Even with only one-treatment a beautiful bright sary, is freed from grease, is slightly corroded brown is b If the whole procedure (inwith Small quantities of solution elusive of .the slight corrosion by means of the 40 listing of F hydrochlonc i and copper acid solution) is carried out several times, all 40 sulphate, is freed from the acid residues still color gradations up to deep da k br wn can be adhering to it and is treated with a stream of produced 'according to the number of'repeflgas containing ammonium sulphide insuch mantiona Any t clouding which may arise ner that the stream of gas sweepsover the are removed ith t tr ble by lightly rubbing metal surface, whereby an immediate brown coldown th a polishing powder (for example 45 Nation 15 obtained- I f Vienna chalk, etc), or by lightly W p A pr rred nst u ti a f m of an appa-- with the above-mentioned copper sulphate soluratus suitable for carrying out the process act containing hydrochloric acid. Furthermore, cording to the invention is illustrated by way of it has been found that any iridescent blue tones example in the accompanying drawing, in which: which may arise disappear entirely-on the sub- 50 Fig. 1 is a diagrammatic view of the'general sequent coating of the metal with a Protective arran nt of t ppa atus. and lacquer, the color passing over into a pure brown. Figs. 2, 3, v4, and 5 show diagrammatically varl- The production of the stream of gas containing 1 W088 S n which m y be emp oyed for ammonium sulphide may be eflected according the Dome hereinaftfl i to, to choice by means of compressed air I or a simple rubber hand-blower 2. Furthermore, the outlet nozzle 8 of the bottle 4, 5, 1, 8 may be adapted to all purposes of employment by the provision of suitable cross sections (round, oval, rectangular, slit-like and so forth-see Figs. 2, 3, 4, and 5). For actuating the blowing device other gases apartfrom air may also .be employed so long as they do not cause any considerable decomposition of the ammonium sulphide.

The hereinbefore described new bronzing process renders it possible to give a uniform brown color to objects made of copper and copper alloys, and particularly brass and special brass in a quicker, simpler and cheaper manner than was hitherto possible. For this purpose no expensive vessels are necessary and the size of the workpieces is not of importance. Moreover the work.

may be carried out either in the workshop or also in situ, for example, on building sites. The process likewise renders possible the renovation of bronzings which have be ome damaged, as also the subsequent coloring i brown of soldered parts. Any desired color tone between light and dark brown can be obtained in the simplest way.

I claim:

1. Process for the bronzing of copper and copper alloys, particularly brass and special brass, comprising in steps: polishing the metal surface to be bronzed; treating said metal surface so as to free it from grease; slightly corroding said metal surface by applying to it small quantities of an acid solution consisting of water, hydrochloric acid and copper sulphate and made up in the proportion of 1000 cc. water, 20 cc. concentrated hydrochloric acid and 20 grammes crystalline copper sulphate; removing acid residues adhering to said metal surface; and treating said metal surface with a stream of gas containing ammonium sulphide in such manner that the stream of gas sweeps over the said surface, whereby an immediate brown coloration is obtained.

2. Process for the bronzing of copper and copper alloys, particularly brass and special brass,

comprising in steps: polishing the metal surface to be bronzed; slightly corroding said metal surface by applying to it small quantities of an acid solution consisting of water, hydrochloric acid and copper sulphate and made up in the proportionof 1000 c. 0. water, 20 c. c. concentrated hydrochloric acid and 20 grammes crystalline copper sulphate; removing acid residues adhering to said metal surface; and treating said metal surface with a stream of gas containing ammonium sulphide in such manner that the stream of gas sweeps over the said surface, whereby an immediate brown coloration is obtained.

3. Process for the bronzing of copper and copper alloys, particularly brass and special brass, comprising in steps: polishing the metal surface to be bronzed; slightly corroding said metal surface by applying to it small quantities of an acid solution consisting of water. hydrochloric acid and copper sulphate and made up in the proportion of 1000 cc. water, 20 cc. concentrated hydrochloric acid and 20 grammes crystalline copper sulphate; removing acid residues adhering to said metal surface; and treating said metal surface with a stream of gas containing ammonium sulphide in such manner that the stream of gas sweeps over the said surface, whereby an immediate brown coloration is obtained; said stream of gas being produced by leading air under pressure through a 10-20% solution of ammonium sulphide, thereby saturating the air with ammonium sulphide, and directing the air saturated with ammonium sulphide on to said metal surface which is to be bronzed.

4. Process for the bronzing of copper and copper alloys, particularly brass and -pecial brass,

comprising in steps: polishing the metal surface to be bronzed; slightly corroding said metal surface by applying to it small quantities of an acid solution consisting of water, hydrochloric acid and copper sulphate and made up in the proportion of 1000 cc. water, 20 cc. concentrated hydrochloric acid and 20 grammes crystalline copper sulphateyremoving acid residues adhering to said metal surface; and treating said metal surface with a stream of gas containing ammonium sulphide in such manner that the stream of gas sweeps over the said surface, whereby an immediate brown coloration is obtained; said stream of gas being produced by leading air discharged from a compressed air container through a 10-20% solution of ammonium sulphide, thereby saturating the air with ammonium sulphide, and directing the air saturated with amonium sulphide on to said metal surface which is to be bronzed.

5. Process for the bronzing of copper and copper alloys, particularly brass and special brass, comprising in steps: polishing the metal surface to be bronzed; slightly corroding said metal surface by applying to it small quantities of an acid solution consisting of water, hydrochloric acid and copper sulphate and made up in the proportion of 1000 c. 0. water, 20 c. c. concentrated hydrochloric acid and 20 grammes crystalline copper sulphate; removing acid residues adhering to said metal surface; treating said metal surface with a stream of gas containing ammonium sulphide in such manner that the stream of gas sweeps over the said surface, whereby an immediate brown coloration is obtained; and after-treating said surface slightly with said acid solution, whereby any cloud or spot formation in the bronz ing is eliminated.

moms BRUNNER. 

